Treating rheumatoid arthritis with micromotors

Rheumatoid arthritis is a chronic inflammatory disorder marked by joint pain, swelling and damage. Although medications, such as steroids, anti-inflammatory drugs and immunosuppressants, can help slow joint destruction and ...

Droplets perform daredevil feats on gel surfaces

Welcome to the amazing world of soft substrates. These materials are made of silicon gels and have the same texture as panna cotta—but without the delicious flavor. They are used in a range of applications, especially in ...

Selective concentration of cationic species

Sample pretreatment processes such as concentration or classification are essential to finding trace substances present in a fluid. In scientific communities recently, prolific research is being conducted on sample pretreatment ...

Cloud simulations get a dose of realism

A cloud simulation that captures the development and evolution of clouds based on atmospheric physical processes is more accurate than other models.

Keeping it fluid: Probing how fluids behave in weightlessness

NASA astronaut Victor Glover installs the Fluid Dynamics in Space experiment, or Fluidics for short. Fluidics is the black cylinder pictured in the foreground of the European Columbus module of the International Space Station.

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In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress, no matter how small. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids.

In common usage, "fluid" is often used as a synonym for "liquid", with no implication that gas could also be present. For example, "brake fluid" is hydraulic oil and will not perform its required function if there is gas in it. This colloquial usage of the term is also common in medicine and in nutrition ("take plenty of fluids").

Liquids form a free surface (that is, a surface not created by the container) while gases do not. The distinction between solids and fluid is not entirely obvious. The distinction is made by evaluating the viscosity of the substance. Silly Putty can be considered to behave like a solid or a fluid, depending on the time period over which it is observed. It is best described as a viscoelastic fluid. There are many examples of substances proving difficult to classify. A particularly interesting one is pitch, as demonstrated in the pitch drop experiment currently running at the University of Queensland.

This text uses material from Wikipedia, licensed under CC BY-SA